The objective of this research component of the Resource is how to achieve interaction with running molecular dynamics simulations and steer the structure to assume an alternate conformation. We have constructed a system that includes three components: a simulation engine (based on SIgMA, under development as part of the resource), a graphical display and interaction system for dynamic molecular models (based on the VMD system developed at UIUC), and a communication protocol between the two systems (using TCP/IP). Technical changes in the project include migration of both simulation and display codes to an SGI Power Challenge server owned by the resource. This has improved simulation performance, which is critical to the usability of the system, by a factor of 2-3 over the previous Challenge and HP 735 compute platforms. In addition, the shared memory provided by the SGI yields very low latency communication between the components, so that responsiveness and interactivity is greatly improved. User interface logic has migrated completely into the display code, VMD, rather than the earlier split between VMD and SIgMA. This has also improved responsiveness and makes changes in the interface easier to code. Jan Hermans has changed SIgMA to support the X-PLOR force field and data file formats, and work on the SScorin de novo protein has been moved to this format. This has made preparation of databases for simulation easier and faster, notably the residue mutations used by our clients to study alternative SScorin designs. Research work has focused on the timescale and energetic effects of manipulations. Adding non-physical external "tugging" forces to a dynamics simulation can cayse significant change of the statistical behavior of the system in terms of solvent structure near the protein surface and local temperature fluctuations. To minimize these disruptive effects, the design cycle will proceed by first specifying a protein manipulation interactively, and next repeating the manipulation (as a batch calculation) at a slower rate which may then proceed along a physically more plausible path. To understand and control these effects, we have specified several representative manipulation tasks which are repeated with different tug forces and timescales. SIgMA has been instrumented to measure kinetic energies in regions near the manipulation. We are starting to analyze time to task completion, overall effects on the system, and localized effects as a function of tug strength. This should lead to semi-empirical constraints on speed of manipulation and a deeper understanding of what it means to tug on proteins. multipole-accelerated algorithms. (Board, Rankin, Lambert, Toukmaji)